1. Field of the Invention
This invention relates to new and useful improvements for conversion of cellulosic wastes into a form which is more edible and digestible by ruminant animals.
2. Brief Description of the Prior Art
Crop residues, i.e., cellulosic wastes, such as cotton gin trash, straw, corn stalks and husks, cotton wastes, peanut shells, saw dust, etc., offer a tremendous feed resource for ruminant animals. For each pound to corn, wheat, milo, etc., produced there is left a cellulosic residue of about one pound. A small amount of these residues are used as animal feed, e.g., by grazing of fields after harvesting the grain.
These cellulosic wastes, such as cotton gin trash, straw, corn stalks and husks, cotton wastes, peanut shells, saw dust, etc., are highly lignified cellulose structures which are digested poorly, if at all, by ruminants. For example, cotton gin trash is only digested about 36%-44% by ruminants as compared to 55-60% for conventional forage such as alfalfa and 80-90% for grains. Some of these ligno-cellulosic wastes, e.g., cotton gin trash, are useful only for their thermal value from burning and have a zero or negative economic value.
It has been known for forty years that the lignin in cellulosic wastes is responsible for the low digestibility. Recently, work at the University of Illinois, University of Nebraska and Texas Tech University has shown that the lignin in cellulosic wastes can be broken down by treatment with alkaline hydrogen peroxide to produce a cellulosic residue which is 55-75% digestible. The problem in utilization of this treatment has been one of logistics as well as the additional expense of the hydrogen peroxide in the quantities required.
The cellulosic wastes derived from agricultural practices are readily available on the farm, or at cotton gins in the case of gin trash, but these materials are bulky and expensive to transport. It is therefore uneconomical to move the dispersed cellulosic wastes to chemical processing facilities. The only practical way, at present, to treat these wastes would involve treatment and consumption of the treated materials on the farm. Central processing might be practical, however, in the case of cotton gin trash, because of the large quantities collected at central locations. The economics of the alkaline hydrogen peroxide treatment is another matter. Even in the quantities used, hydrogen peroxide is expensive and the cost of treatment makes the entire process of treatment economically doubtful. The development of a cheap process for manufacture of hydrogen peroxide at the point of use on the farm might overcome these economic constraints.
The following references are relevant to the production of oxidizers and their use in chemically treating agricultural wastes. R. Norris Shreve, "Chemical Process Industries" 3rd Ed., McGraw-Hill, New York, N.Y. pp. 222-259, (1967); "Kirk Othmer, Encyclopedia of Chemical Technology" 3rd Ed. vol X5, 580-611, Interscience Publishers, New York, N.Y. (1968); Wendell Latymer, "Oxidation Potentials" Prentice Hall, New York, N.Y. (1952); Michael Andon "Oxygen" W. A. Benjamim, New York, N.Y. (1965); C. R. Wilke, et. al., "Enzymatic Hydrolysis of Cellulose, Theory and Application" pp. 41-61, Noyes Data Corporation Park Ridge, N.J. (1983); and David A. Tillman and Edwin C. John "Progress in Biomass Conversion" Volume 4, Academic Press, New York, N.Y. (1983).
Charles T. Sweeney, U.S. patent application Ser. No. 328,278, filed Mar. 24, 1989, has recently conducted and sponsored research into the use of various mixed oxidant gases in the conversion of cellulosic wastes which offers the prospect of overcoming both the reagent cost and logistical problems encountered in the preparation of ruminant feeds. This research has involved the utilization of various mixed oxidant gases produced by various electrolytic cells.
Chlorine generators based on the use of electrolytic cells for production of chlorine for chlorinating bodies of water are shown in Murray U.S. Pat. No. 2,361,663, Oldershaw U.S. Pat. No. 3,351,542, Colvin U.S. Pat. No. 3,378,479, Kirkham U.S. Pat. No. 3,669,857, and Yates U.S. Pat. No. 4,097,356. These electrolytic cells are disclosed in a variety of configurations and most of the cells utilize ion-permeable membranes separating the anode and cathode-containing compartments.
Ion-permeable membrane technology used in electrolytic cells is well developed Ion-permeable membranes used in electrolytic cells have ranged from asbestos diaphragms to carboxylate resin polymers to perfluorosulfonic acid polymer membranes. The perfluorosulfonic acid membranes were developed by Dupont for use in electrolytic cells. Anion exchange membranes, of polymers having anion functionality, are made by Ionics Inc. of Watertown, Mass.
Dotson U.S. Pat. No. 3,793,163 discloses the use of Dupont perfluorosulfonic acid (NAFION) membranes in electrolytic cells and makes reference to U.S. Pat. Nos. 2,636,851; 3,017,338; 3,560,568; 3,496,077; 2,967,807; 3,282,875 and British Patent 1,184,321 as disclosing such membranes and various uses thereof.
Walmsley U.S. Pat. No. 3,909,378 discloses another type of fluorinated ion exchange polymer used in membranes for electrolytic cells for electrolysis of salt solutions.
Further discussion of membrane technology used in electrolytic cells may be found in Butler U.S. Pat. No. 3,017,338, Danna U.S. Pat. No. 3,775,272, Kircher U.S. Pat. No. 3,960,697, Carlin U.S. Pat. No. 4,010,085, Westerlund U.S. Pat. No. 4,069,128 and Sweeney U.S. Pat. No. 4,804,449.
Discussion of perfluorosulfonic acid (NAFION) membranes is also discussed in the technical literature, e.g., Dupont Magazine, May-June 1973, pages 22-25 and a paper entitled "Perfluorinated Ion Exchange Membrane" by Grot, Munn and Walmsley, presented to the 141st National Meeting of the Electro-Chemical Society, Houston, Tex., May 7-11, 1972.
The structure of electrodes used in electrolytic cells is set forth in most of the patents listed above. Additionally, the following U. S. Patents disclose configurations of anodes or cathodes used in electrolytic cells.
Giacopelli U.S. Pat. No. 3,375,184 discloses an electrolytic cell with controllable multiple electrodes which are flat plates of wedgeshaped configuration. Ettel U.S. Pat. No. 3,821,097 uses flat plates in electroplating cells. Lohrberg U.S. Pat. No. 3,951,767 discloses the use of flat plate electrolytic anodes having groove along the bottoms thereof for conducting gas bubbles generated in the electrolytic process. Andreoli U.S. Pat. No. 565,953 discloses electroplating apparatus having a plurality of metal screens which are not connected in the electric circuit and function to plate out the metal being separated by the electrolysis.
In "The chlorine dioxide content of chlorine obtained by electrolysis of salt", Electrochemical Technology 5, 56-58 (1967) Western and Hoogland report that chlorine dioxide is not produced in the electrolysis of salt in the absence of chlorates.
Sweeney U.S. Pat. No. 4,256,552 discloses an electrolytic generator for production of chlorine, for chlorination of swimming pools, water systems, etc., in which a bipolar electrode is positioned in the anode compartment between the anode and the cation-exchange membrane in the wall separating the compartments. Sweeney U.S. Pat. No. 4,334,968 discloses improvements on the cell or generator of U.S. Pat. No. 4,256,552 and discloses the production of chlorine dioxide in the cell. Sweeney U.S. Pat. No. 4,248,681 discloses a method of producing chlorine/chlorine dioxide mixtures in the cells of U.S. Pat. Nos. 4,256,552 and 4,334,968 and gives some optimum operating conditions. Sweeney U.S. Pat. No. 4,308,117 discloses a cell having three compartments, with the anode and cathode in the outer compartments and the bipolar electrode in the central compartment. A cation-exchange membrane is positioned in the wall between the central compartment and the cathode compartment, while an anion-exchange membrane is positioned in the wall between the central compartment and the anode compartment. Sweeney U.S. Pat. No. 4,324,635 discloses a cell having an anode compartment, a cathode compartment, and a separating wall with a cathode-exchange membrane therein. The cell includes a pump circulating some of the cathode compartment solution to the anode compartment for pH control. The gases produced by these cells have come to be referred to as mixed oxidant gases which contain chlorine, oxides of chlorine, oxygen as ozone, peroxides, and other oxygen species.
In subsequent studies, it has been found that cells of the type shown in U.S. Pat. Nos. 4,256,552, 4,334,968 and 4,248,681 can be operated with very low salt concentrations and, under such conditions, produce oxidizing gases containing very small amounts of chlorine or chlorine compounds. Sweeney U.S. Pat. No. 4,804,449 discloses the use of nonionic membranes of Kanecaron in place of Nafion in electrolytic cells for production of mixed oxidant gases. Kanecaron fibers are of a modacrylic composition of acrylic polymeric structure having 35-85% wt. acrylonitrile units. Kanecaron fibers used in these cells are modacrylic fibers of this general type composed of 50% acrylonitrile and 50% vinyl chloride fibers.